The present invention relates to an ink stamp having a printing sheet.
There is a type of ink stamp including a printing sheet that is impregnated with ink such that the ink stamp may be used a relatively large number of times without replenishing the ink. FIGS. 1A and 1B are a sectional view and a perspective view of the printing sheet. The printing sheet 139 is made of a porous resin sheet 138 on which a print portion 138A and a non-print portion 138B are formed. The print portion 138A allows the permeation of the impregnated ink whereas the non-print portion 138B blocks the permeation of the impregnated ink.
FIG. 2 shows the process for manufacturing the printing sheet 139. A mask sheet 136 is placed on a transparent base plate 125, which includes a pattern portion 136A which blocks the electromagnetic waves and a non-pattern portion 136B which allows the electromagnetic waves to pass. A black film 137 is placed on a mask sheet 136 and the porous resin sheet 138 is placed above the black film 137. Then, a flash bulb 115 is flashed and infrared light rays (shown by arrows) are irradiated onto the lower surface of the mask sheet 136. Infrared rays irradiated onto the pattern portion 136A on the mask sheet 136 are blocked by the pattern portion 136A, whereas infrared rays irradiated onto non-pattern portion 136B pass through the mask sheet 136. The infrared rays passing through the mask sheet 136 reach the black film 137 causing the black film 137 to generate heat. The heated surface of the porous resin sheet 138 is caused to melt such that pores near the surface thereof are sealed. Conversely, since the infrared rays are blocked by the pattern portion 136A of the mask sheet 136, the portion of the black film 137 which corresponds to the pattern portion 136A does not generate heat, so that the pores near the surface of the porous resin sheet 138 corresponding thereto are not sealed. Thus, the print portion 138A and the non-print portion 138B are formed on the porous resin sheet 138 producing the printing sheet 139.
However, in the conventional manufacturing process, the black film 137 must be interposed between the mask sheet 136 and the porous resin sheet 138 to act as a heating element. As such, the manufacturing process requires the positioning of the black film 137 between the porous resin sheet 138 and the mask sheet 136. Thus, the use of the black film 137 increases the manufacturing cost of the printing sheet 139.